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    <title>Document</title>
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    <script>
        // 算术运算符
        console.log(1 + 2 * 3 / 2) //  4 
        let num = 10
        console.log(num + 10)  // 20
        console.log(num + num)  // 20
        // 取模(取余数)  使用场景：  用来判断某个数是否能够被整除
        console.log(4 % 2) //  0  
        console.log(6 % 3) //  0
        console.log(5 % 3) //  2
        console.log(3 % 5) //  3
        // 注意事项 : 如果我们计算失败，则返回的结果是 NaN (not a number)
        console.log('helloworld' - 2)
        console.log('helloworld' * 10)
        console.log('helloworld' + 2)  
        
        //NaN:not a Number
        let value = NaN ; 
        console.log(value);
         console.log(typeof NaN);
        //NaN:关于NaN的任何运算都返回NaN.
        console.clear();
        console.log(NaN+5);
        console.log(NaN*5);
        console.log(NaN-5);
        console.log(NaN/5);
    </script>
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